The present invention has for its object processes for transmitting video signals from a video camera to a television set, video cameras for carrying out these processes and applications of these cameras.
The technical sector of the invention is that of the construction of static video cameras intended in particular for watching or for local uses, or of mobile cameras.
In numerous applications such as the watching of premises, stores, banks, appartments, etc . . . , fixed cameras are used, distributed in the premises, which transmit signals to video monitors located in a watching station.
Transmission of the signals between the cameras and the video monitors is generally effected by cables in order not to disturb reception of the public television broadcasts which are transmitted by Hertzian waves on determined channels.
Exceptionally, the authorities in charge of controlling use of the carrier frequencies may allow a local transmission by Hertzian waves on a well-determined carrier frequency, which is free in the emission zone, but such authorizations are difficult to obtain and cannot be multiplied.
The development of technologies makes it possible at the present time to construct video cameras for watching having very good performances for a reduced cost.
However, the transmission of the signals by cables between the camera and the video monitors involves considerable expenses and limits the applications of the watching cameras.